1. Field of the Invention
The present invention is directed to an anchor assembly for retaining a medical instrument within an anatomical cavity, wherein the anchor assembly comprises a mechanical attachment of an inflatable member to the exterior of the medical instrument. The mechanical attachment eliminates or at least minimizes the reliance on adhesive and other conventional types of connections, thereby greatly reducing the assembling and manufacturing costs, while eliminating or significantly reducing the failure or inadvertent detachment of the inflatable member from its operative position on the instrument.
2. Description of the Related Art
The use of various types of anchoring devices on medical instruments, in order to maintain the instrument on the interior of a body cavity or in a predetermined location relative to other organs of the body, is well known. One prevalent category of anchoring devices includes the use of an inflatable “balloon” or like member formed of an expandable material and secured to an exterior portion of the instrument with which it is associated. Examples of medical instruments incorporating such inflatable anchoring devices include trocars, which are used in laparoscopic or endoscopic surgery, and in particular, the cannula portion of the trocar, as well as retention catheters.
In this latter category, i.e., retention type catheters, a flexible or resilient body portion has an elongated inflating lumen which directs fluid (e.g., gas) under pressure into an interior the inflatable balloon or like structure. Upon inflation, the balloon will extend radially outward so as to effectively retain the catheter in the intended position. Similarly, trocar structures are used in minimally invasive surgical procedures. In use, a cannula portion of the trocar enters a body cavity and is effectively retained or “anchored” into an intended position by subjecting the interior of the anchoring balloon to pressurized fluid.
Previously, the elastic material from which the inflatable balloons or like members were formed was a rubber or latex material. As such, the degree of pressurization of the inflating fluid was maintained within certain acceptable limits. However, more recently the inflatable balloons or like structures have been formed of a plastic material including, but not limited to, polyurethane, polyvinyl chloride and various copolymers thereof. It was soon discovered that balloons formed from the aforementioned types of plastic materials require higher inflation pressures than conventional latex balloons. While the inflating fluid could easily be supplied to the interior of the balloon or other inflatable retention device at an increased pressure, other disadvantages or problems associated therewith developed.
More specifically, the structural features associated with the attachment or securement of the inflatable anchors to the exterior of the medical instrument are recognized as being problematic. The aforementioned disadvantages are primarily associated with failure or malfunctioning of the inflatable member by virtue of them becoming detached when expanded or inflated, not unlike the “blow-out” of a tire. As a result, a variety of different techniques, wrapping or winding structures, etc. were developed in an attempt to provide a reliable means of attaching an inflatable member to the cannula portion of a trocar, while not overly complicating the manufacturing process for such anchoring devices.
Known structures associated with the attachment of inflation anchors or like expandable structures typically include the use of adhesives, molding and/or heat sealing techniques, which may used independently or in combination with one another. In addition, an inflatable anchoring structure associated with known, commercially available trocar assemblies utilizes an adhesive securement in combination with a wrapping or binding of wound suturing material. The suturing material is applied to opposite ends or other appropriate portions of the inflatable retention device in order to maintain its secured engagement on the exterior of the cannula portion of the trocar or other type of instrument.
Despite the extensive time and effort dedicated to the effective attachment or mounting of an inflatable, balloon type retention member on medical instruments, the above set forth problems and disadvantages associated with the costs of assembly and manufacture as well as the rate of failure of such anchoring devices still exists. More specifically, detachment problems associated with inflatable anchors as used on a variety of known and commercially available trocar assemblies, retention catheters, etc., is all too common. Therefore, there is a significant and long recognized need for an anchoring assembly capable of being used on a trocar or other medical instrument which is safe, reliable and which is not unduly expensive or complicated to manufacture and produce. If any such improved anchoring assembly were developed, it should be capable of stabilized and reliable attachment to an exterior or other appropriate portion of an associated medical instrument in a manner which overcomes the problems associated with conventional or known inflatable retention devices. In addition, any such improved anchor assembly would ideally include the attachment of an inflatable member to an instrument in a manner capable of consistently withstanding inflating gases supplied at commonly used or increased pressures.